Most people get the three "R"s of green living: Reduce, reuse, recycle. Here's a fourth: Repurpose—As in turning a wine barrel into a hotel room or using glass bottles to decorate a temple. Repurposed buildings save material by reusing existing structures—it's also called adaptive reuse—or recycling otherwise landfill-bound objects as building materials. Here's what repurposing looks like around the world: